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Bike Fit Technical Terms


JJDT
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I bought my son a road bike and went to competitive cyclist to get details of bike fitment. I do not understand those technical terms can somebody explain me these terms and what to do. Below is the layout.

 

Thanks

 

The Competitive Fit The Eddy Fit The French Fit

Seat tube range c-c 54.4 - 54.9 55.6 - 56.1 57.3 - 57.8

Seat tube range c-t 56.1 - 56.6 57.3 - 57.8 59.0 - 59.5

Top tube length 52.0 - 52.4 52.0 - 52.4 53.2 - 53.6

Stem Length 10.5 - 11.1 9.4 - 10.0 9.6 - 10.2

BB-Saddle Position 75.9 - 77.9 75.1 - 77.1 73.4 - 75.4

Saddle-Handlebar 49.8 - 50.4 50.6 - 51.2 52.3 - 52.9

Saddle Setback 4.8 - 5.2 6.0 - 6.4 5.5 - 5.9

Explanation of Fit Calculator Output Values

1. Seat Tube Range C-C

Your new bike's seat tube height should fall within this range. "Center-to-Center" signifies the length of the seat tube as measured from the center of the bottom bracket spindle to the midpoint of where the seat tube intersects the top tube. The seat tube height is most important as it relates to your head tube. If your seat tube is too short, your head tube will almost certainly be too short. This results in too low of a handlebar position placing an inordinate amount of stress on your neck and back. For this very reason, if you feel as though you could go with either of two sizes, going with the bigger frame is normally advisable. Please keep in mind that many frames come with a sloping or "compact" frame geometry in which the C-C seat tube measurement is artificially short. In the case of compact frames, you should primarily focus on the top tube measurement.

2. Seat Tube Range C-T

"Center-to-Top" signifies the length of the seat tube as measured from the center of the bottom bracket spindle to the top of the seat tube where it intersects the top tube.

3. Top Tube Range

This measurement is along the top tube, from the midpoint at the seat tube to the midpoint at the head tube. No single piece of frame geometry has a greater impact on comfort than your top tube. If you plan on paying attention to one measurement and one measurement only, make it this one. Keep in mind that we do not measure the actual top tube on bikes with compact frame geometry. Rather, we use an "Effective Top Tube" measurement - an imaginary line drawn parallel to the ground along the length of the top tube.

4. Stem Length

This measurement indicates your ideal stem length. It takes into account that your stem will be flipped to its flatter angle (e.g. 80° for Deda, 84° for Ritchey).

5. BB-Saddle Position

This measurement is along the seat tube, from the center of the bottom bracket spindle to the top of the saddle. It is an ideal starting point for saddle height. Given the varying differences of cleat and pedal heights, and given the varying differences in the thickness of saddles, the BB-Saddle position has a broad range of 2cm.

6. Saddle-Handlebar

This measurement ties together your choice of stem length with your saddle setback. It is measured from the nose of the saddle to the near edge of your handlebar. Keeping within this range will assure that you don't accidently push the weight balance of your bike either too far forward or backward.

7. Saddle Setback

This measurement is primarily a function of your femur length. The longer your femurs, the further your saddle needs to be behind the bottom bracket in order to allow you to produce power. If you sit too far forward (or too far back) you can over-emphasize certain muscles and joints, which robs you of power and can potentially cause you injury. Saddle setback is measured by dropping a plumb bob from the nose of your saddle and measuring how far behind the center of the bottom bracket it falls. This is not to be confused with the setback measurement of your frame, which is a measurement taken by dropping a plumb bob from the center of your seat tube/top tube interface, and measuring how far behind the center of the bottom bracket it falls.

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I bought my son a road bike and went to competitive cyclist to get details of bike fitment. I do not understand those technical terms can somebody explain me these terms and what to do. Below is the layout.

 

Thanks

 

The Competitive Fit The Eddy Fit The French Fit

Seat tube range c-c 54.4 - 54.9 55.6 - 56.1 57.3 - 57.8

Seat tube range c-t 56.1 - 56.6 57.3 - 57.8 59.0 - 59.5

Top tube length 52.0 - 52.4 52.0 - 52.4 53.2 - 53.6

Stem Length 10.5 - 11.1 9.4 - 10.0 9.6 - 10.2

BB-Saddle Position 75.9 - 77.9 75.1 - 77.1 73.4 - 75.4

Saddle-Handlebar 49.8 - 50.4 50.6 - 51.2 52.3 - 52.9

Saddle Setback 4.8 - 5.2 6.0 - 6.4 5.5 - 5.9

Explanation of Fit Calculator Output Values

1. Seat Tube Range C-C

Your new bike's seat tube height should fall within this range. "Center-to-Center" signifies the length of the seat tube as measured from the center of the bottom bracket spindle to the midpoint of where the seat tube intersects the top tube. The seat tube height is most important as it relates to your head tube. If your seat tube is too short, your head tube will almost certainly be too short. This results in too low of a handlebar position placing an inordinate amount of stress on your neck and back. For this very reason, if you feel as though you could go with either of two sizes, going with the bigger frame is normally advisable. Please keep in mind that many frames come with a sloping or "compact" frame geometry in which the C-C seat tube measurement is artificially short. In the case of compact frames, you should primarily focus on the top tube measurement.

2. Seat Tube Range C-T

"Center-to-Top" signifies the length of the seat tube as measured from the center of the bottom bracket spindle to the top of the seat tube where it intersects the top tube.

3. Top Tube Range

This measurement is along the top tube, from the midpoint at the seat tube to the midpoint at the head tube. No single piece of frame geometry has a greater impact on comfort than your top tube. If you plan on paying attention to one measurement and one measurement only, make it this one. Keep in mind that we do not measure the actual top tube on bikes with compact frame geometry. Rather, we use an "Effective Top Tube" measurement - an imaginary line drawn parallel to the ground along the length of the top tube.

4. Stem Length

This measurement indicates your ideal stem length. It takes into account that your stem will be flipped to its flatter angle (e.g. 80° for Deda, 84° for Ritchey).

5. BB-Saddle Position

This measurement is along the seat tube, from the center of the bottom bracket spindle to the top of the saddle. It is an ideal starting point for saddle height. Given the varying differences of cleat and pedal heights, and given the varying differences in the thickness of saddles, the BB-Saddle position has a broad range of 2cm.

6. Saddle-Handlebar

This measurement ties together your choice of stem length with your saddle setback. It is measured from the nose of the saddle to the near edge of your handlebar. Keeping within this range will assure that you don't accidently push the weight balance of your bike either too far forward or backward.

7. Saddle Setback

This measurement is primarily a function of your femur length. The longer your femurs, the further your saddle needs to be behind the bottom bracket in order to allow you to produce power. If you sit too far forward (or too far back) you can over-emphasize certain muscles and joints, which robs you of power and can potentially cause you injury. Saddle setback is measured by dropping a plumb bob from the nose of your saddle and measuring how far behind the center of the bottom bracket it falls. This is not to be confused with the setback measurement of your frame, which is a measurement taken by dropping a plumb bob from the center of your seat tube/top tube interface, and measuring how far behind the center of the bottom bracket it falls.

 

So you bought the bike and now you are trying to make you son fit the bike :lol:

 

The explanation they give can't really be any better, look at the sketch on the site while reading the info, will make more sense then.

 

Next time try and fit the bike to your son ;)

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Hi, I am 1.79M with inside leg of 87mm.. will a 17"KTM be too small for me??

 

Inside leg of 87mm, so your whole leg goes into your shoe?! Trip over your shlong much?

 

Any bike will be too big for you I'm afraid!

Edited by Tankman
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So you bought the bike and now you are trying to make you son fit the bike :lol:

 

The explanation they give can't really be any better, look at the sketch on the site while reading the info, will make more sense then.

 

Next time try and fit the bike to your son ;)

 

Thanks for the reply will look into it....words are not my strong point but I will try next time to fit the bike to my son :-)

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OK so I have figured it all out now I'm confused again. The saddle handlebar adjusts the tip of the seat to the edge of the handlebar but then saddle setback could either then adjust your saddle forward or backwards depending on the measurements. By doing this you will adjust the saddle-handlebar out again. :huh:

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